{{Short description|Genus of bacteria}} {{About||the settlement in Algeria|M'Lili|the Roman colony in Hispania|Acci}} {{Automatic taxobox | parent_authority = Chuvochina et al. 2024 | taxon = Gemella | authority = Berger 1960<ref name=LPSN/> | type_species = ''Gemella haemolysans'' | type_species_authority = (Thjøtta & Bøe 1938) Berger 1960 | subdivision_ranks = Species | subdivision_ref = <ref name=NCBI/> | subdivision = * ''G. asaccharolytic'' * ''G. bergeri'' * ''G. cuniculi'' * ''G. haemolysans'' * ''G. massiliensis'' * ''[[Gemella morbillorum|G. morbillorum]]'' * ''[[Gemella palaticanis|G. palaticanis]]'' * ''G. parahaemolysans'' * ''[[Gemella sanguinis|G. sanguinis]]'' * ''G. taiwanensis'' | synonyms = * ''Gemelliphila'' <small>Bello et al. 2024</small> }}
'''''Gemella''''' is a genus of [[Gram-positive]] [[bacteria]] that thrive best at high [[partial pressure]] of [[carbon dioxide|CO<sub>2</sub>]].
==Description==
A ''Gemella'' species was first described as ''Neisseria hemolysans'' in 1938.<ref>{{Cite journal|title = Neisseria hemolysans. A Hemolytic Species of Neisseria trevisan|last1 = Thjøtta |first1=T |last2=Bøe |first2=J |date = 1938|journal = Acta Pathologica et Bacteriologica Scandinavica Supplement |volume= 37 |pages=527–531}}</ref> It was reclassified as a new genus in 1960 when strains were found to be distinct enough from Neisseria to require a new genus.<ref>{{Cite journal|title = A proposed new genus of gram-negative cocci: Gemella|journal = International Bulletin of Bacteriological Nomenclature and Taxonomy|date = 1961-01-01|pages = 17–19|volume = 11|issue = 1|doi = 10.1099/0096266x-11-1-17|first = U.|last = BERGER|doi-access = free}}</ref> The name was suggested based on the organism being a [[diplococcus]] and gemellus is the diminutive of geminus, which is Latin for twin.{{Cn|date=February 2025}} They are [[facultative anaerobe|facultatively anaerobic]] and give negative reactions to both [[oxidase]] and [[catalase]] tests. They are obligately [[Fermentation (biochemistry)|fermentative]], producing either a mixture of [[acetic acid|acetic]] and [[lactic acid|lactic]] acids or an equimolar molar mixture of acetic acid and CO<sub>2</sub>. For example, ''G. haemolysans'' ferments [[glucose]] forming a mixture of acetic and lactic acids in the absence of [[oxygen]], whereas when oxygen is present, it forms acetic acid and CO<sub>2</sub>.<ref>{{cite journal |author= Stackebrandt, E. |author2= B. Wittek |author3= E. Seewaldt |author4= K. H. Schleifer |name-list-style= amp |title=Physiological, biochemical and phylogenetic studies on ''Gemella haemolysans'' |journal=FEMS Microbiology Letters |volume=13 |pages=361–365 |year=1982|doi= 10.1111/j.1574-6968.1982.tb08288.x |issue= 4 |doi-access= free }}</ref>
==Clinical importance==
''Gemella'' bacteria are primarily found in the [[mucous membrane]]s of humans and other animals, particularly in the [[oral cavity]] and upper [[digestive tract]]. ''Gemella haemolysans'' has been found to be involved in pulmonary exacerbations of [[cystic fibrosis]] patients.<ref>{{Cite journal|title = Changes in Cystic Fibrosis Airway Microbiota at Pulmonary Exacerbation|journal = Annals of the American Thoracic Society|date = 2013-06-01|issn = 2329-6933|pmc = 3960905|pmid = 23802813|pages = 179–187|volume = 10|issue = 3|doi = 10.1513/AnnalsATS.201211-107OC|first1 = Lisa A.|last1 = Carmody|first2 = Jiangchao|last2 = Zhao|first3 = Patrick D.|last3 = Schloss|first4 = Joseph F.|last4 = Petrosino|first5 = Susan|last5 = Murray|first6 = Vincent B.|last6 = Young|first7 = Jun Z.|last7 = Li|first8 = John J.|last8 = LiPuma}}</ref> As of the year 2000 it had been reported in 15 cases of human [[endocarditis]], mainly in men with underlying [[Valvular heart disease|valvular disease]] and/or poor dentition or dental manipulation. Most cases were treated with a combination of penicillin and gentamicin with a favorable outcome.<ref>{{Cite journal|title = Endocarditis due to Gemella haemolysans in a patient with hemochromatosis|journal = Clinical Microbiology and Infection|pages = 566–568|volume = 6|issue = 10|doi = 10.1046/j.1469-0691.2000.00136.x|first1 = J.D.|last1 = Mosquera|first2 = M.|last2 = Zabalza|first3 = M.|last3 = Laniero|first4 = J.R.|last4 = Blanco|year = 2000|doi-access = free| pmid=11168056 }}</ref> Additionally, ''Gemella asaccharolytica'' in bacterial vaginosis is associated with increase risk of HIV infection in unprotected sex.
==Phylogeny== The currently accepted taxonomy is based on the [[List of Prokaryotic names with Standing in Nomenclature]] (LPSN)<ref name=LPSN>{{cite web |author=A.C. Parte |url=https://lpsn.dsmz.de/genus/gemella |title=Gemella |access-date=2025-02-28 |publisher=[[List of Prokaryotic names with Standing in Nomenclature]] (LPSN) |display-authors=et al.}}</ref> and [[National Center for Biotechnology Information]] (NCBI).<ref name=NCBI>{{cite web |author=C.L. Schoch |url=https://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Tree&id=1378&lvl=3&lin=f&keep=1&srchmode=1&unlock |title=Gemella |access-date=2025-02-28 |publisher=[[National Center for Biotechnology Information]] (NCBI) taxonomy database |display-authors=et al.}}</ref>
{| class="wikitable" |- ! colspan=1 | 16S rRNA based [[The All-Species Living Tree Project|LTP]]_10_2024<ref>{{cite web |title=The LTP |url=https://imedea.uib-csic.es/mmg/ltp/#LTP| access-date=10 December 2024}}</ref><ref>{{cite web |title=LTP_all tree in newick format |url=https://imedea.uib-csic.es/mmg/ltp/wp-content/uploads/ltp/LTP_all_10_2024.ntree |access-date=10 December 2024}}</ref><ref>{{cite web |title=LTP_10_2024 Release Notes |url=https://imedea.uib-csic.es/mmg/ltp/wp-content/uploads/ltp/LTP_10_2024_release_notes.pdf |access-date=10 December 2024}}</ref> ! colspan=1 | 120 marker proteins based [[Genome Taxonomy Database|GTDB]] 09-RS220<ref name="about">{{cite web |title=GTDB release 09-RS220 |url=https://gtdb.ecogenomic.org/about#4%7C |website=[[Genome Taxonomy Database]] |access-date=10 May 2024}}</ref><ref name="tree">{{cite web |title=bac120_r220.sp_labels |url=https://data.gtdb.ecogenomic.org/releases/release220/220.0/auxillary_files/bac120_r220.sp_labels.tree |website=[[Genome Taxonomy Database]] |access-date=10 May 2024}}</ref><ref name="taxon_history">{{cite web |title=Taxon History |url=https://gtdb.ecogenomic.org/taxon_history/ |website=[[Genome Taxonomy Database]] |access-date=10 May 2024}}</ref> |- | style="vertical-align:top| {{Clade | style=font-size:90%;line-height:80% |label1=''Gemella'' |1={{clade |1=''G. taiwanensis'' <small>Hung et al. 2014</small> |2={{clade |1=''G. haemolysans'' <small>(Thjøtta & Bøe 1938) Berger 1960</small> |2={{clade |1=''G. parahaemolysans'' <small>Hung et al. 2014</small> |2={{clade |1=''[[Gemella sanguinis|G. sanguinis]]'' <small>Collins et al. 1999</small> |2={{clade |1=''[[Gemella morbillorum|G. morbillorum]]'' <small>(Prévot 1933) Kilpper-Bälz & Schleifer 1988</small> |2={{clade |1=''G. cuniculi'' <small>Hoyles et al. 2000</small> |2={{clade |1={{clade |1=''G. bergeri'' <small>corrig. Collins et al. 1998</small> |2=''G. massiliensis'' <small>Mbogning Fonkou et al. 2023</small> }} |2={{clade |1=''G. asaccharolytic'' <small>Ulger-Toprak et al. 2010</small> |2=''[[Gemella palaticanis|G. palaticanis]]'' <small>Collins et al. 1999</small> }} }} }} }} }} }} }} }} }} | {{barlabel |size=0 |at1=-2 |label1=''Gemelliphila'' |bar1=green |at2=1.5 |label2=''Gemella'' s.s. |bar2=green |cladogram= {{Clade | style=font-size:90%;line-height:80% |label1=''Gemella'' |1={{clade |1={{clade |1=''G. asaccharolytic''|barbegin1=green |2=''[[Gemella palaticanis|G. palaticanis]]''|barend2=green }} |2={{clade |1={{clade |1=''G. bergeri''|barbegin1=green |2=''G. massiliensis''|bar2=green }} |2={{clade |1=''G. cuniculi''|bar1=green |2={{clade |1=''[[Gemella sanguinis|G. sanguinis]]''|bar1=green |2={{clade |1=''[[Gemella morbillorum|G. morbillorum]]''|bar1=green |2=''G. haemolysans''|barend2=green }} }} }} }} }} }} }} |}
==References== {{Reflist}}
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[[Category:Bacillales]] [[Category:Bacteria genera]]
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